Conventionally, for example, in automobile electric components such as automobile lamps and ECUs (Electrical Control Units), OA (office automation) equipment, household electric appliances, and medical devices, a housing containing an electric component or a control board is provided with an opening for the purpose of reducing pressure variation in the housing caused by temperature change or allowing replacement of air in the housing, and a ventilation member is attached to the opening. The ventilation member ensures ventilation between the inside and outside of the housing and also prevents foreign matters such as dust and water from entering the housing.
For example, Patent Literature 1 discloses a ventilation member 100 as shown in FIGS. 6A and 6B. The ventilation member 100 includes: a water-proof gas-permeable membrane 120 for covering an opening 151 of a housing 150; a support 110 supporting the water-proof gas-permeable membrane 120 and configured to be fixed to the housing 150; and a cover component 130 covering the water-proof gas-permeable membrane 120.
The support 110 has a tubular shape as a whole, and includes: a flange portion 112 to which the water-proof gas-permeable membrane 120 is adhered; and an insertion portion 111 projecting from the flange portion 112 and configured to be inserted into the opening 151 of the housing 150. A sealing member 140 is mounted around the root portion of the insertion portion 111. The sealing member 140 is pressed against the housing 150 by the flange portion 112, so that a gap between the ventilation member 100 and the housing 150 is sealed.
The cover component 130 includes: a principal wall 131 facing the water-proof gas-permeable membrane 120; and a peripheral wall 132 extending from the peripheral portion of the principal wall 131 to the vicinity of a surface of the housing 150. In addition, the principal wall 131 is provided with through holes 133 for allowing a space facing the water-proof gas-permeable membrane 120 to communicate with the outside.
In addition, Patent Literature 2 discloses a ventilation structure 300 in which partition walls 152 are provided on the housing 150 so as to surround a ventilation member 200 as shown in FIGS. 7A and 7B. The partition walls 152 are arc-shaped walls spaced from each other, and have a height greater than that of the ventilation member 200.